Tt-qtt



F. LOWENSTEIN. SPARK GAP DEVICEA APPLICATION FILED AIIG.25. IQIIy Pafenred June 3, 1919.

2 SHEETS-SHEET l.

F. LOWENSTEIN.

SPARK GAP DEWCE.

APPLICATION HLED Aue.2s, |914.

. Patented .lune 3, 1919.

2 SHEETS SHEET 2.

FRITZ LOWNSTEIN. 0F BROOKLYN, NEW YORK.

SPARK-GAP DEVECE.

Specification of Letters Eatent.

Patented June 3, igig.

Application led August 25. 1914. Serial No. 858,499.

To all 'whom it may concern.'

Beit known that l, FRITZ LOWENSTEIN, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in SparkGap Devices, of which the following is a specication.

This invention relates to spark gaps for,

use especially in wireless or radio signalingV installations; and it has to do more particularly with spark gaps of the general type known as quenched gaps.

The principal objects of the invention are: to provide spark gap apparatus of relatively simple construction, the component parts or essential elements of which shall be individually removable and replaceable when necessity arises withoutl disassembling the spark gap structure as a whole; to provide for easy and rapid adjustment of the spark length to suit dii-ferent operating conditions; to provide a spark gap clement or unit of novel form and particularly advantafveous characteristics; and to insure elli-,cient quenching and uniform lengtl. of the spark gap. Other objects ot' the invention will appear as the description proceeds.

In order to illustrate. clearly the principles of the invention, the application thereof specifically to spark gaps for wireless telcgraphy will be more particularly referred to herein. this being at present the most important use for which the invention is adapted.

ln the usual types of wireless telegraph systems now in practical use, the, apparatus at the sending' station comprises an antenna included. in what is known as the open or radiating circuit, to which circuit energy is supplied by a Vclosed or oscillating circuit suitably supplied with alternating current irom any convenient source. rThis oscillating circuit comprises inductance, a conA denser, and a spark gap across which sparks are made to pass when it is desired to radiate signals from the antenna. The character and construction or the parts constituting this spark gap is a matter of great importance since the nature of the sparks produced, and consequently the operation of the whole sending system. are profoundly inlluenced thereby. The present. invention is directed principally to improvements in spark gaps adapted. for use in this way in wireless telegraphy.

One of the principal requirements to be inet in a spark gap device is the necessityY for cooling the electrodes of the gap in o1.'- der that they may be insulated from each other with the utmost rapidity after each spark discharge passing between them. Various methods of cooling the gap electrodes have been proposed heretofore, but they have not been altogether satisfactory and have generally involved more or less complicated construction of the electrodes or auxiliary parts.

In a practical form of the present invention the sparks pass between a pair or pairs ot parallel cylindrical .surfaces of ample arca suitably insulated from each other and best formed in such manner as to favor very rapid dissipation of heat Jfrom the surfaces in question. The term cylindrical as herein employed is to be understood in a broad sense as including prismatic as well as strictly cylindrical surfaces. though right cylindrical surfaces proper are much the best in practice. Furthermore the invention in its broadest aspects contemplates the use ot' other types of surfaces such as conical or spherical surfaces which may be so arranged and spaced apart with substantial uuiforni ity as to provide an air grap substantially annular in cross section: the term annular to he understood moreover as not restricted to a true circular annulus. but as applying' broadly to areas included between two curves or polygons more or less concentrically arranged. A spark gap of this characier is herein Ytermed broadly a tubular spark gap For the sake oiE a concrete example and in order to explain clearly the principles of the invention thus hroadly deiinedan especially desirable practical einbodiu'ient thereof :is illustrated in the drawings and is hereinafter descrihed in detail. such illustrative embodiment comprising! a pair ol hollow right cylindrical shells or tubes arranged coaxially one within the other. and suitably spaced apart and insulated from each other to provide between adjacent suriaces an annular gap or space o? uniform width.

lt is also desirable in practice te divide the total requisite length ot1 the spark gap in the oscillating circuit into a plurality of relatively small component or elementary gaps arranged in series Whose combined or aggregated lengths equal operatively the length of spark gap necessary. Among the advantages of this general type of construction are the quenching of the oscillations in the closed circuit and more or less complete elimination of noise from the spark. Various forms of quenched gap have been proy posed heretofore; but, among other defects,

they have the disadvantage that if any of the component gap elements have .to be removed for repair or replacement.v this cannot be effectedv without disturbing other gap elements in the series, and practically taking apart and reassembling the complete gap structure. Such a procedure involves loss of considerable time which may cause a fatal delay under some circumstances; and it also involves expert work which may not be conveniently available.

This and other defects inherent in quenched gaps as heretofore proposed are obviated in my improved construction herein described in which the component gap elements, which are broadly of the tubular type above disclosed, are so assembled and mounted that any spark gap element or unitis individually removable and replaceable practically in an instant without disturbing or removing any other component unit of the complete gap structure, and without the exercise of any special skill on the part of an attendant operator. Furthermore the arrangement is such that the number of component spark gap elements or units in the series may be readily varied at will to adjust the total spark length in response to working requirements.

These and other important features and advantages of the present improved spark gap apparatus will be more fully pointed out in the following detailed description and in the claims, particular reference being had to the accompanying drawings which are to be understood as illustrating, for the 1 sake of an example, certain particularly advantageous forms of apparatus in which the principles of the invention may be embodied. In these drawings Figure 1 is a view in side elevation of a tubular spark gap device constructed inaccordance with the invention;

Figs. 2 and 3 are longitudinal and trans verse sections, respectively, of the same;

Fig. 4 is a view of one face of a base or holder on which a plurality of spark gaps are mounted;

Fig. 5 is a view of the opposite or rear face of the switch board, some of the gap units havingkbeen removed to show the. connections more clearly;

Fig. 6 shows the switch board assembled with a cooling drum and fan;

such as copper and are spaced apart and inj sulated from each other by insulating rings 14, each of which is slotted or channeled along one side to accommodate an end of the outer shell or sleeve. Each insulating ring is thus divided into two connected parts, 16 and 17 whose parallel inner faces 18 and 19 engage the convex surfaces of the outer and inner shells, respectively. The parts 17 of the insulating rings extend between and space apart the shells to form the spark gap; and the outer faces 20 of these parts may be slightly sloped or beveled as shown. The insulating` rings may be locked in place as by means of threaded collars 21 Which are adapted to be turned down on threaded portions 12 and 13 of the inner shell into locking abutment with said rings. When the rings are in proper position they abut against shoulders 22 and 23 on the outer and inner shells respectively. This-form of joint between the insulating rings and the shells or electrodes insures that the spark gap space is sealed substantially air tight, which is desirable. The seal persists even when the electrodes become heated and expand; for in the event of such expansion the electrodes press against the ring surfaces 18 and 19, which are similarly located as regards resistance offered to the radial thrust of the shell expansion, and the tightness of the joint is therefore maintained.

The method of construction just described unites the pair of electrode shells into a compact and substantially unitary spark gap element, adapted to be inserted as a distinct unit into series with other similar units, or to be removed as a unit from such series. In the present example, the longer threaded extension 13 of the inner electrode serves vconveniently in connecting the spark gapelement in such a series, as will be more fully hereinafter described. Obviously variousother expedients could be adopted for this purpose.

Another advantage secured by this construction is that the clamping pressure of terminal rings 14 and collars 21 is exerted in a direction parallel to the gap surfaces, so that the width of the gap is independent of the clamping pressure. Where gap electrodes are held by clamping means exertfaces, as in constructions heretofore known,

monete the width of the' gap, and hence the performance of the sending system, varies with the degree of clamping pressure. This disadvantage is evidently avoided in the present device.

As shown, the central or intermediate portions 24 of the electrodes are formed in such a Way that the annular spark gap space is narrower at this locality than toward the ends; and it is at this locality that the sparks actually pass betweenthe electrodes.

nnular circumferential ribs 10a and 11 formed on the electrodes 10 and 11, res ectively, project into the wider portions o the gap space andare in staggered or non-registering arrangement. These ribs act as baffles to prevent particles of metalI from being spattered or otherwise transferred-from the spark to the insulating surfaces-at the lends of thegap, thus preventing deposit of `to the grooves and in close proximity thereto.

Since these heat-dissipating surfaces are parallel to and coextensive with the elementary spark gap included between them, and are "separated from said gap only by the thickness of the copper electrode walls, the heat developed in the gap has only to pass directly inwardly and outwardly from the gap through said walls in the direction of their thickness, and is thus dissipated with maximum efliciency. In multiple gap constructions heretofore commonly used, in which the gap was made up of parallel fiat plates spaced apart to form a series of gap elements, the heat from each elementary gap had to be transmitted parallel to the gap to the outer peripheries of the plates, being thus conducted a much greater distance than in the present tubular construction.

Various methods may be adopted for connecting up a. number of these tubular gaps in series to obtain any desired total spark length, but that illustrated Vin Figs. 4, 5 and 6 has proved particularly desirable in practice. A circular disk 3G of insulating material serves as a mounting base and switch board and supports provided, but obviously any other convenient or necessary number may be used. With the exception of the terminal socket 31, the socket-s are electrically connected in pairs, in this instance by means ofnmetal bars 32 formed integral with and supporting the sockets of each pair, said bars being bolted or otherwise suitably secured to the rear side of the board. Double spring contacts 33 are mounted on the board so as to press against and electrically connect in pairs the outer shells or electrodes of spark gap units' screwed into adjacent but electrically unconnected socket rings. Spring contact 33a connects the outer shell of the spark gap element at one end of the series to terminal binding post 34; while 'socket ring 31a and its bar connect the inner shell of the gap element at the other end of the series to terminal binding post 35. The arrangement is such that the spark gap elements are connected in series between the terminals 34 and 35, at which terminals the necessary connections may be made to include the complete spark gap in the oscillating circuit of a sending apparatus. p

On the opposite or front side ci' the board, contact points 36 are electrically connected to and represent intermediate points in the respective connections 32 between the inner shells of each connected pair; while contact points 37 similarly represent intermediate points in the outer shell air connections 33. Conductor 38 connects binding post 35 with a central post 39 and a rotatable switch or contact arm 40 carried thereby and operable by means of an insulated handle 41. This switch is arranged to move over and contact withthe circular series of switch points 36, 37; and in the showing of Fig. 4, when the switch is moved clockwise (counter-clockwise lin Fig. 7), it short-circuits one by one an increasing number of gap elements, thus shortening the total eective spark length. When the switch is turned in the opposite direction, more gap elements are brought into circuit and the effective spark length is thereby increased.

lThe switch points may conveniently be numbered serz'wzfz'm so that the-number of gap elements in series at any time is indicated by the number of the point with which the switch is in contact at that time.

/If for any reason one of the spark gaps is not working properly, it can be quickly unscrewed from its socket and replaced by another spark gap with hardly a moments delay, the necessary connections of its electrodes to the rest of the series being auto matically made in the act of inserting it into its socket.

rihe edge ci the switchboard may be shouldered as at 41P- for engagement with the end of a drum 42 of insulating mate- -rial, attachment being aided by threaded studs 43 and win nuts 44. A motor driven fan 45 is arrange to draw air into the drum through openings 46 in the board adjacent the socket rings or holders. These openings are best of somewhat greater diameter than Ithe tubular spark. gaps and are substan- .lar spark`- gaps terminally attached to said base, openings extending through said base adjacent the ends of said spark gaps, and means for causing iow of air through said openings and longitudinally of said spark gaps.

2. Spark gap apparatus comprising an insulating disk, holders mounted thereon and electrically connected in pairs, tubular spark gaps each having an outer and all lmer electrode shell of which the latter is removably secured to -a holder, and' means electrically connecting in pairs the outer shells of those spark gaps whose inner shells are not connected in pairs by the holder connections.

the arrangement being such that the spark '-prising the combination with' supporting gaps are connected in series.

3. Quenched spark gap apparatus comprising a plurality .of gap units electrically connected in series and so mounted that each of the units is individually removable in dependently of the others, in combination With's'witch means operable to include a variable Vnumber of said units etl'ectively in circuit.

4. QuenchedV spark gap apparatus comprising a plurality of coperating spark electrodes electrically connected to provide asuitable number of elementary gaps in series, said electrodes being arranged in a plurality. of separate gap structures, each individually removable from the complete gap ap aratus without disturbing the others, 1n combination with switch means operable to include a variable number of said separate gap structures in circuit.

5. Quenched spark gap apparatus commeans, of a plurality of spark gap elements supported thereby, and electricall connected 1n series, a plurality of switc contacts connected to dierent points in the series of gap elements, switch means movable to engage said contacts, and means for connecting said switch means and a point in said series roil ap elements to a power circuit, whereby t e effective number of gap elements in circuit, may be varied.

6. Quenched spark gap apparatus com-- prising the combination, with a supporting base provided with a plurality ol-Z apertures, o f a plurality of tubular spark gap members each supported in longitudinal alinecontacts, and'a fan arranged to move air*` longitudinally of said gap members.

7 A spark gap holder comprising, in combination, an insulating base, a plurality of gap unit supports mounted thereon and arranged to connect in series removable spark gap units, and switch means adapted for connection in an oscillation circuit and operable to make electrical connection with different supports of said plurality, said switch means being mounted on said base.

8. A spark gap holder comprising, in combination, an insulating base, a plurality of gap unit supports mounted thereon and arranged to connect in series removable spark gap units, contacts connected to said supports, and switch means adapt-ed for connection in an oscillation circuit and arranged to coperate with said contacts.

9. A spark gap device comprising coperating electrode members spaced apart to prvide a suitable gap and separated by insulating means, said device embodying provision for shielding said insulating means from direct exposure to the gap.

l0. A' tubular spark gap device comprisin inner and outer conducting shells in su stantially coaxial arrangement, and insulating members spacing sald shells apart to provide a spark gap, said device embodying provision for shielding said insulating members from direct exposure to the gap.

- v11. A tubular spark gap device comprising inner and outer conducting shells in sub; stantially coaxial arrangement, insulating rings spacing said shells apart to Provide, 'a spark gap, baie means shielding said rings from direct exposure to the gap, and means for securing said insulating rings in position and cooperating therewith to secure said shells together.

12, A tubular spark ap device comprising inner and outer 'cy indrical conducting shells in substantially coaxial arrangement, insulating rings arranged near the ends of said shells and spacing them apart to form a tubular spark gap of greater width adjacent the ends than in an intermediate locality, and ribs projecting from said shells into the wider portions of 'the spark gap.

mesme A 5 i3. Spark gap apparatus eompising a ln testimony whereof l have signed this supporting plate of insulating material, a speciicatin in the presence oit' two sub- 10 casing cflosel :lit one eijiid by sald plate, a pluseribing Witnesses. Talty o tu u ar spar gap e ements mount- 1 ed. in line with suitable apeltures in said FREE LWENSTEN plate and electrically connected in series, Witnesses: and a fan arranged to move air through P, B. Pilules, saiol easing to cool the gap elements. CHRISTY CROWLEY. 

